Process for bleaching cotton with aqueous alkaline bleaching baths and the products obtained thereby



United States Patent 3,193,507 F1012 BLEACHTPJG CGTTON WITH AQUEGTE ALKAHNE ELEACHKNG BATE-IS THE iR-QDUCTS QBTAHNED Heinz Grunert, Dusseldorf ti ersten, Germany, assignor to ii-ohme Fett l emie G.rn.b.l-l., Dusseldorf, Germany, a corporation 0; Germany No Drawing. Filed dune 25, 1962, Ser. No. 205,106 Claims priority, application Germany, July 21, 1961, B 63,363 12 Claims. (Ci. 8 111) The invention relates to an improved process for the preparation of surgical cotton which has excellent absorptive properties and a silk-like scroop,

The raw material for surgical cotton, such as raw natural cotton, cotton linters, etc., is subjected to several separate steps to achieve satisfactory absorptive properties and to give the cotton fibers a silk-like scroop. The said cotton is usually subjected to a caustic kier-boiling treatment or a boiling-off treatment, then to a bleaching step, and finally to another treatment in another bath to obtain the si k-like scroop effect.

it is an object of the invention to provide an improved, simplified process to obtain surgical cotton.

It is another object of the invention to provide a process to obtain surgical cotton wherein excess scrooping agents can be removed by rinsing.

It is a further object of the invention to provide an improved surgical cotton having high absorption properties and silk-like scroop.

These and other objects and advantages of the invention will become obvious from the following detailed description.

The process of the invention for the preparation of highly absorptive surgical cotton having sil"-like scroop comprises treating the raw cotton material with an aqueous alkaline bath containing a wetting agent at a temperature of 40 to 80 0., preferably about 60 (3., adding to the said bath bleaching and scrooping agents, heating the resulting bath stepwise at intervals up to a temperature of about 120 C., cooling the bath to below 100 C., rinsing the cotton fibers with warm water and then cold water, and drying the cotton to obtain the said surgical cotton. The treatment with the wetting agent can be performed before or after the addition of the bleaching and scrooping agents.

This method of treatment represents a very significant simplification of the previously known process in that a kier-boiling or boiling-off treatment can be entirely omitted. Moreover, it is unexpected that the cleansing treatment of the raw cotton and the scrooping treatment could be performed in the same bath, and that the scroop effect would be completely retained in the subsequent rinsing step. in addition, it is a particular advantage of the present process that excess scrooping agent can be recovered from the fiber by the rinsing step. The highly absorptive cotton fibers having silk-like scroop are eminently suitable for manufacture of sanitary and medicinal cotton goods.

The preliminary wetting bath is an aqueous alkaline solution containing 1 to 3 g./l. of a wetting and dispersing agent, preferably a nonionic, surface active compound. Examples of suitable nonionic, surface active agents are alkyl polyglycol ethers formed by the condensation of an alkyl alcohol having 8 to 18 carbons with an alkylene oxide, such as ethylene oxide, and alkyl phenol-polyglycol ether formed by the condensation of an alkyl phenol wherein the alkyl radical has 4 to 12 carbon atoms with an alkylene oxide such as ethylene oxide. The alkaline solution is preferably an aqueous solution containing 3- l0 g./l. of an alkali metal hydroxide such as sodium hydroxide.

The bleaching agents for cotton are well known and any of the usual agents may be used. Examples of suitable agents are alkali metal perborates, persulfates, etc, and hydrogen peroxide which is preferred. Concentrations of l to 10 g./l. of the bleaching agents give a satisfactory whiteness.

Agents which impart a silk-like scroop effect to cotton are well know. Examples of scrooping agents are polyglycol ethers of high molecular weight compounds having exchangeable hydrogen atoms such as hydroxyl, carboxylic acid, and amino compounds such as oleyl amine stearic acid, oleyl alcohol. Especially useful for the invention are mixtures of unsaturated fatty alcohols having 12 to 18 carbon atoms and alkyl polyglycol ether condensation products of 1 mole of fatty alcohols having 12 to 14 carbon atoms with 6 to 12 moles of ethylene oxide. Concentrations of l to 3 g./l. of the scrooping agent give satisfactory results.

The stepwise heating of the bath is preferably effected in a closed pressure vessel in 2 to 5 steps, preferably 3 steps, for intervals of 10 to minutes each. For example, the steps may be effected at temperatures of about 60 C., 80 C., and then 120 C. for time intervals of 10 to 30 minutes each. After the stepwise heating, the bath is cooled to below 100 C. and the cotton fibers are rinsed with warm water and then cold water, and then dried in the usual manner. Excess scrooping agent is removed from the cotton fibers by the rinsing.

In the following examples there are described sevral preferred embodiments to illustrate the invention. iowever, it should be understood that the invention is not intended to be limited to the specific embodiments.

Example I kg. of cotton linters were subjected to a preliminary wetting treatment in a solution of 1000 liters of water, 1 kg. of a condensation product of 1 mol of fatty alcohols having 12 to 14 carbon atoms and 8 to 10 mols of ethylene oxide and 3 kg. of 38 Be. sodium hydroxide for about 20 minutes at 60 C. Then, 4 kg. of 35% hydrogen peroxide and 1 kg. of a mixture of 5 parts of unsaturated sperm oil fatty alcohols having 14 to 18 carbon atoms and 1 part of a condensation product of 1 mol of fatty alcohols having 12 to 18 carbon atoms and 8 to 12 mols of ethylene oxide were added to the said solution. The cotton was treated in this solution for ten minutes at 60 C. Thereafter, the temperature of the solution was increased to 80 C. over a period of 10-15 minutes, main tained for 20 minutes at 80 C., raised over 20 minutes to 120 C. in the closed vessel, and maintained at that level for an additional 20 minutes. Subsequently, the solution was cooled to 90 C., the cotton was removed and rinsed first in warm and then in cold water. After drying, an absorptive cotton fiber having a silk-like scroop was obtained.

Example II kg. of raw cotton were subjected to a preliminary wetting treatment in a solution of 1000 liters of water, 5 kg. of 38 B. sodium hydroxide and 2 kg. of the condensation product of 9 mols of ethylene oxide with 1 mol of nonyl phenol for about 20 minutes at C. Then, 5 kg. of 35% hydrogen peroxide and 3 kg. of the condensation product of 6 mols of ethylene oxide with 1 mol of stearic acid were added to the said solution. The cotton was treated in this solution for 10 minutes at 60 C. Thereafter, the temperature of the solution was raised to C. over a period of about 1015 minutes, maintained at 80 C. for 20 minutes, raised to 120 C. within 20 minutes in the closed vessel and held at that level for an additional 20 minutes. The solution was then cooled to C., and the cotton was rinsed in first hot and then t cold water, and then dried to obtain a highly absorptive cotton fiber with a silk-like scroop.

The example was repeated except that the hydrogen peroxide and the condensation product were added to the preliminary wetting bath before the raw cotton was treated. A highly absorptive cotton with a silk-like scroop was again obtained.

Various modifications of the process of the invention may be made without departing from the spirit or scope thereof, and it is to be understood that the invention is to be limited only as defined in the appended claims.

I claim:

1. A process for the preparation of highly absorptive surgical cotton having a silk-like scroop which comprises treating the raw cotton material in a preliminary wetting step with an aqueous alkaline bath containing a nonionic, polyoxyalkylene oxide condensation wetting agent at a temperature of 40 to 80 C., adding a bleaching agent and a scrooping agent to the said bath, heating the resulting bath and raw cotton stepwise up to about 120 C., cooling the bath to below 100 C., rinsing the cotton with first Warm water and then cold water, and drying the cotton to obtain the said highly absorptive surgical cotton.

2. The process of claim 1 wherein the bleaching agent and the scrooping agent are added to the aqueous alkaline bath before the preliminary wetting step.

3. The process of claim 1 wherein the stepwise heating is effected in three steps at temperatures of about 60 C., 80 C. and 120 C. for to minutes each.

4. The process of claim 1 wherein the bleaching agent is hydrogen peroxide.

5. The process of claim 1 wherein the preliminary wetting step is effected at 60 C.

6. A process for the preparation of a highly absorptive surgical cotton having a silk-like scroop which comprises treating the raW cotton material in a preliminary wetting step with an aqueous sodium hydroxide solution containing the condensation product of 1 mol of fatty alcohol having 12 to 14 carbon atoms and 8 to 10 mols of ethylene oxide at about 60 C. for 10 to 30 minutes, adding to the bath hydrogen peroxide and a mixture of unsaturated sperm oil fatty alcohols having 14 to 18 carbon atoms and the condensation product of 1 mol of fatty alcohols having 12 to 18 carbon atoms and 8 to 12 mols of ethylene oxide, heating the resulting solution and cotton material for periods of 10 to 30 minutes at temperatures of about C., C. and 120 C., cooling the bath to below C., rinsing the cotton material with warm water and then cold water and drying the cotton to obtain the said highly absorptive surgical cotton.

7. The process of claim 6 wherein the hydrogen peroxide and the mixture of fatty alcohols and condensation product is added to the aqueous sodium hydroxide solution before the preliminary wetting step.

8. A process for the preparation of a highly absorptive surgical cotton having a silk-like scroop which comprises treating the raw cotton material in a preliminary wetting step with an aqueous sodium hydroxide solution containing the condensation product of 1 mol of nonyl phenol and 9 mols of ethylene oxide at about 60 C. for 10 to 30 minutes, adding to the bath hydrogen peroxide and the condensation product of 1 mol of stearic acid and 6 mols of ethylene oxide, heating the resulting solution and cotton material for periods of 10 to 30 minutes at temperatures of about 60 C., 80 C. and C., cooling the bath below 100 C., rinsing the cotton material with warm water and then cold water and drying the cotton to obtain the said highly absorptive surgical cotton.

9. The process of claim 8 wherein the hydrogen peroxide and the aryl condensation product are added to the aqueous sodium hydroxide solution before the preliminary wetting step.

10. The product produced by the process of claim 1.

11. The product produced by the process of claim 6.

12. The product produced by the process of claim 3.

References Cited by the Examiner UNITED STATES PATENTS 2,126,809 8/38 Pratt 8-125 2,190,331 2/40 Mosher 1l7139.5 2,344,259 3/44 Morgan et a1. 260239.3 2,482,917 9/49 Kaplan 106135 2,473,577 6/49 De Groote et al 260309.6 3,027,223 3/62 Teot 8-125 3,081,181 3/62 Rutenberg et a1 128-296 X OTHER REFERENCES Speel et al.: Textile Chemicals and Auxiliaries, 2nd ed., 1957, pages 119 and 120, Reinhold Publishing Corporation, New York.

NORMAN G. TORCHIN, Primary Examiner. 

1. A PROCESS FOR THE PREPARATION OF HIGHLY ABSORPTIVE SURGICAL COTTON HAVING A SILK-LIKE SCROOP WHICH COMPRISES TREATING THE RAW COTTON MATERIAL IN A PRELIMINARY WETTING STEP WITH AN AQUEOUS ALKALINE BATH CONTAINING A NONIONIC, POLYOXYALKYLENE OXIDE CONDENSATION WETTING AGENT AT A TEMPERATURE OF 40 TO 80*C., ADDING A BLEACHING AGENT AND A SCROOPING AGENT TO THE SAID BATH, HEATING THE RESULTING BATH AND RAW COTTON STEPWISE UP TO ABOUT 120*C., COOLING THE BATH TO BELOW 100*C., RINSING THE COTTON WITH FIRST WARM WATER AND THEN COLD WATER, AND DRYING THE COTTON TO OBTAIN THE SAID HIGHLY ABSORPTIVE SURGICAL COTTON. 